Electric signaling system



"R. L. QUASS. ELECTRIC SIGNALING SYSTEM-- APPLICATION man Nov. 12, 1919.

1,394,642, Patented Oct. 25, 1921.

/0 2M??? za sflf RALPH L. QUASS, OF HAWTHORNE, NEW JERSEY, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC SIGNALING SYSTEM.

- Specification of Letters Patent.

Patented Oct. 25, 1921.

Application filed November 12, 1919. Serial No. 337,594.

To all whom it may concern:

Be .it known that I, RALPH L. QUASS, a citizen of the United States, residing at Hawthorne, in the county of Passaic, State of New Jersey, have invented certain new and useful Improvements in Electric Signah ing Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to electric signaling systems wherein the existence of an unstandard condition is automatically signaled to an attendant. 7

Its object is the provision of an improved circuit arrangement for systems of this character which will be cheap to manufacture and to maintain and which will be reliable in operation.

The invention is particularly applicable to machine switching telephone exchange systems. In such systems a call being set up may progress to a certain switch in the series which fails to function properly. This failure should be automatically indicated to an attendant who will thereupon ascertain the cause.

A feature of the invention is the provision of an arrangement whereby rapidly succeeding grounds on the circuit to be supervised are ineffective to operate the alarm signal. Thus one signal may serve a number of i switch circuits without danger of false indications.

In the present embodiment a. pair of'electro-responsive timing devices are employed through one of which a circuit is closed when the common lead from the switch beingsupervised is grounded due to one of the switches being taken for use. This device,

after an interval, operates, opens its circuit and closes a circult includlng the second timing device. After another interval this device operates and causes the closure of the alarm circuit. If, however, before the second device has had time to operate the ground is removed, the circuit of the second device is opened and that of the first device is again closed, which device in the meantime has returned to its normal condition. Thus the cumulative eflect of succeeding short impulses is prevented. The arrangement may therefore be used very advantageously with a number of switches since all false operations except those created by a large number of overlapping switch operamon lead, the succeeding ground must not only be long enough to operate the first and second device before the alarm signal is operated, but must also last long enough to cause the relay to fully attract its armature.

Referring to the drawing which diagrammatically represents a circuit arrangement embodying the invention as applied to a machine switching telephone exchange system -w1tl1 subscribers control, A represents the calling substation connected to the central ofliceby conductors 8 and 9, which terminate in multiples 10 and 11 of a number of automatic finder switches. A test multiple 12 is provided for each line in the finders in which it appears. 13, 14 and 15 represent the brushes of the finder which automatically seek the calling line and extend the same to the first selector FS.

The invention will be most readily understood by describing the operations involved in setting the selector. WVhen the calling subscriber removes his receiver from the switchhook and operates the sender S for the first digit of the called number, the stepping relay 16 operates in the well-known manner transmitting impulses to the primary stepping magnet PM over the follow ing circuit: grounded armature and back contact of relay 16, armature l7 and back contact of relay 18, conductor 19, armature 20 and front contact of slow relay 21, which becomes energized upon the operation of relay 16, relay 22, magnet PM, free pole of battery. Magnet PM steps the selector to the desired group of trunks. The relay 22 operates in series with the primary magnet and being of the slow-to-release type, maintains its armature attracted during the transmission of the impulses. This relay in attracting its armature operates relay 23, which looks itself to ground over the following path: free pole of battery, relay 23, its armature and front contact, conductor 24, right armature and back contact of secondary magnet SM, off-normal contact 25,

closed by the selector shaft at the beginning of its movement, conductor 26 to ground at the outer left armature and contact of slow relay 21.

When the sender restores, relay 22 after a short interval retracts its armature closing the following circuit for secondary magnet SM to step the switch over the trunk group in search of an idle trunk: free pole of battery, magnet SM, its left armature and back contact, armature and back contact relay 22, armature and front contact of relay 23, conductor 24, right armature and back contact of magnet SM, off-normal contact 25, conductor 26, outer left armature and front contact of relay 21 to ground. Magnet SM advances the brushes 27, 28, 29 of the selector into engagement with the first trunk, and at the end of the attractive movement of its right armature opens its own circuit and the locking circuit of relay 23. If this trunk is busy, ground is present on the test multiple 33 thereof and thus relay 23 will be maintained energized over a circuit including its armature and front contact, conductor 30, test brush 2'? and the grounded test multiple 33. It will thusbe seen that this relay 23 is maintained energized either over the right armature and back contact of magnet SM or from grounds on the test multiples of busy trunks, and

consequently the stepping magnet SM continues to step the switch past busy trunks. When an idle trunk is reached denoted by the absence of ground on its test multiple 33, relay 23 becomes denergized thus stopping the trunk hunting movement. Upon the seizure of the trunk 31 and 32 a ground is immediately placed, in the well known manner, on the test wire 33 thereof, which causes the relay 18 to operate over a circuit including the armature and'back cont-act of relay 23. This relay 18 in attracting its armatures 34 and cuts off the stepping relay 16 from the calling line and extends the circuit of the calling line to the trunk 31, 32. Before the armature of relay 16 reaches its back contact, the armature 17 has already opened its back contact, and consequently the circuit of release magnet RM is prevented from being prematurely closed. The relay 16 in retracting its armature opens the circuit of the slow relay 21, which releases its armatures.

Assuming, however, that the switch does not properly operate as described and that the relay 16 is not disconnected from the calling line due, for example, to selecting a trunk that is out of order and on which no ground potential is present on the multiple test The relay 16 remaining attracted,

relay 21 consequently holds up its armature and after a predetermined interval, the circuit closed at the right armature and front contact of this relay is effective to operate a relay 1. This relay is so constructed that it is slow to close its front contact. The relay 1 in closing its front contact closes the following circuit including a heat relay 2 and a marginal relay 3: ground, armature and front contact of relay 1, conductors 36, 37, contact 38 of relay 7, contact 39 of relay 4:, conductor 40, relay 3, heat relay 2, free pole of battery. Heat relay 2 after an interval closes its contact 41 which short circuits resistance coil 42, whereupon the relay 3, which is marginal, attracts its armature operating relay 4 over the following circuit: free pole of battery, relay 4;, conductor 4-3, armature and front contact of relay 3, conductor 45, conductor 36, armature and front contact of relay 1 to ground. Relay at in opening contact 39 cuts off heat relay 2 and marginal relay 3 and in closing contact 46 locks itself to ground over the following path: free pole of battery, relay 1, contact 16, contact 38, conductors 37 and 36 to ground at armature and front contact of relay 1. At its left armature relay t connects heat relay 5 and marginal relay 6 to the grounded armature of relay 1. Relay 5 operates, after an interval, closing its contact 457 which short circuits resistance coil -18, whereupon marginal relay 6 operates. This relay inattracting its armature energizes relay 7 over the following path: free pole of battery, relay 7, conductor 19, armature and front contact of relay 6, conductor 36 to the grounded armature and front contact of relay 1. Relay 7 in attracting its right armature unlocks relay 4: and locks itself up to ground at the armature and front contact of relay 1. In attracting its left armature this relay closes the circuit of the signal 50 located before an attendant to indicate to such attendant that the switch has failed to function properly.

By virtue of this arrangement the cumulative effect of rapidly recurring short im-' pulses cannot cause a false indication. Assume, for example, that the relay 21 has been energized long enough to operate relay 1, heat relay 2 and almost long enough to permit heat relay 5 to operate and then the circuit of relay 1' is interrupted. Relay 1 is provided with a dash pot, as shown, so that it attracts its armature slowly and retracts it quickly. In retracting its armature it unlocks relay 4, which reconnects heat relay 2 to the armature of relay 1. If the circuit of relay 1 is again immediately closed, relay 1, being slow to operate, will not close the circuit of heat relay 2 until a sufficient period has elapsed to allow relay 2 to restore and open contact 41. Therefore, in order to operate the signal 50, this impulse must be long enough to operate relay 1, and heat up and operate relays 2 and 5 in succession. By this arrangement the signal 50 can be advantageously associated with a number of selectors with the minimum of danger of false indications. The only chance of a false indication would be due to a number of overlapping grounds on conductor 36, which could be minimized by limiting the number of switch circuitsserved by a given signal.

The release of the selector FS takes place upon the replacing of the receiver by either the calling or the called party which results in the removal of the ground from the conductor 33 and consequent deencrgization of the relay 18. The armature 17 of this relay in closing its back contact operates to release magnet RM over the following circuit: grounded armature and back contact of relay 16, armature 17 and back contact of relay 18, conductor 19, armature 20 and back contact of relay 21, conductor 51, off-normal contact 52, release magnet RM and the free pole of battery. Magnet RM withdraws the holding pawls of the selector, whereupon the selector is restored and upon reaching its normal position again opens the ofli-normal contacts 25, 52.

That is claimed is:

1. In a signaling system, a circuit, means for closing the same, a pair of electroresponsive timing devices, one being included in said circuit and only operated by its closure for a predetermined period, means thereupon operative for removing said device from said circuit and substituting the other timing device, said latter device only operating if the circuit remains closed for a predetermined additional period, said means being released by the opening of said cir- &

cuit prior to the expiration of said additional period and disconnecting said second timing device from said circuit and reconnecting thereto the first timing device, and a signal actuated only upon the successive operations of the first and second timing devices.

2. In a signaling system, a circuit, a pair of electroresponsive timing devices, one being included in said circuit and only operated by its closure for a predetermined period, means operated by said-timing device in op erating for substituting said second timing device in the circuit, a second circuit and a relay in said second circuit controlling a contact in the first named circuit, said relay responding only upon the closure 01 its circuit for a predetermined interval, and a signal actuated by the operation of said second timing device.

3. In a signaling system, a signal, a circuit, a heat relay and a marginal relay included therein, a resistance short circuited by the operation of the heat relay, a second heat relay and marginal relay, means operated by said first marginal relay in operating for disconnecting the marginal relay and heat relay from said circuit and substituting said second heat relay and marginal relay, said latter relay operating upon the operation of the associated heat relay, and means actuated thereby for operating said signal.

In witness whereof, I hereunto subscribe my name this 8th day of November A. D.,

RALPH L. QUASS. 

